Rotary presses are commonly known and are used in a versatile manner in the pharmaceutical industry. They have a rotor, which is mostly driven around a vertical axis, and have upper and lower stamps, dies, circular die plates and cam systems as well as at least one pressing station. When the rotor is rotated, the cam system provides for the vertical positioning of the upper and lower stamps on the partial circle. The filling of the dies with powder-shaped pressing material takes place with the aid of suitable filling systems, a stirring blade equipment or a feeder shoe for instance, so that the dies are continuously filled at rotating rotor. Furthermore, there are preliminary and main pressure rolls, with the aid of which the pressing material is pressed into a tablet. The ejection of the tablets from the dies takes place with the aid of the respective lower stamp, which is actuated by an ejection cam. A stripper strips off the tablets from the topside of the circular die plate to a gravity chute or the like, from which the tablets are lead to a filling station.
From U.S. 2004/0012781 A1, the entire contents of which is incorporated herein by reference, it has become known to equip a reservoir for powder or granulate, assigned to a tabletting machine, from which the tablets are pressed, with a spectroscope. With the aid of the latter, homogeneity and/or humidity of the material are measured. From DE 697 18 811 T2, the entire contents of which is incorporated herein by reference, it has become known to perform spectroscopic analysis by laser irradiation of drug samples. The light emitted from the plasma which is formed by the laser irradiation is given up to an optical spectrometer by an optical system. From U.S. Pat. No. 5,504,332, the entire contents of which is incorporated herein by reference, and U.S. Pat. No. 5,760,399, the entire contents of which is incorporated herein by reference, it has become known to examine the homogeneity of a tablet powder mixture. This method is based on the spectroscopy of the irradiated material.
From DE 10 20004 008321 B3, the entire contents of which is incorporated herein by reference, it has become known to acquire chemical and/or mechanical data with the aid of a NIR- or LIF-sensor in the press room, the pressing process being triggered by a machine computer depending on die positions with respect to the sensor, established by a position transmitter. With the aid of this method, the tablets can be examined online for a plurality of quality parameters, the proportional composition of the tablet material as well as for the hardness thereof in particular and so on.
From EP 0 431 269 B2, the entire contents of which is incorporated herein by reference, it has become known to assign pressing force values to stamps of a rotary press with the aid of an angle impulse generator. The measurement of the pressing force makes it possible to maintain quality criterions, because the pressing force is a measure for the breaking tendency, the tablet weight and the tablet hardness, as is known. In the known method, an angle impulse generator is used, which releases a separate revolution impulse upon revolution of the circular die plate. An encoded signal transmitter is adjusted such that the revolution impulse is released when the pressing force of a certain pressing stamp has reached the maximum value. The angle impulse generator creates at least one continuous impulse series per revolution, which is input into a machine computer. The computer transforms the received impulses into further impulse series, the impulses of which have a distance from each other which corresponds to the distance of the pressing stamps, and the latter impulses are co-ordinated with the indicated maximum pressing force values. Thus, the computer can establish pressing force standard deviations in order to give out evaluations to determine the quality of the production for each tablet.
During the pressing process, energy is naturally introduced into the tablet, the same becoming warmer in this. Some materials to be pressed are thermolabile. During production, a maximum temperature must not be exceeded. In order to accomplish this, it is known to equip tablet presses with cooling installations or to cool down the pressing material itself.
The present invention is based on the objective to provide or indicate, respectively, a device and a method for monitoring the production of tablet presses in a rotary press, by which a detection of the maximum temperature of the tablets during pressing is possible.